nice web site!
from your write up, it sounds like you (might) not yet have an infrared thermometer... these things can often save a bunch of work as usually I can pinpoint the cluster before I start cutting
with the number of cutouts you are posting about, it should be a must have tool... the $40 or 50 that I spent buying one on ebay was well worth it the first time I used it.
I wish that I had so many calls over here on the east side of jefferson county...
tips: buy one with the largest distance to spot ratio you can afford (more accuracy) and mornings are the best time to use one in "difficult" situations because the temp difference between the cluster and the surrounding area will be greatest.